It has been known to convert sunlight into thermal energy by a solar heat collecting apparatus using a heat collecting plate, and to convert sunlight into electrical energy by a solar cell. There has also been proposed a sunlight-into-energy conversion apparatus in which a solar cell serving as a sunlight-into-electricity conversion means has been attached to the heat collecting plate of the solar heat collecting apparatus. However, such proposed solar cell has been constituted by single crystal silicon and has had a thickness of about 300.mu., so that the sunlight could not pass therethrough. Therefore, when such solar cell having a relatively thick thickness is attached to the heat collecting plate of a solar heat collecting apparatus, that portion of the heat collecting plate covered by the solar cell becomes ineffective in collecting solar heat, whereby the sunlight may not effectively be converted into thermal energy.